"IS" — how important is this for the IS exam?

I keep seeing IS come up in every study guide and practice test for (IS) Inbound Sales Certification.

How heavily does it actually appear on the real exam? I've done about 10 full practice tests now and it shows up constantly, which makes me think it's a high-weight topic — but I want to confirm before I go deep on it.

What I've noticed: the questions on "IS" in the practice tests are mostly conceptual, but occasionally they throw in these weird scenario questions where you have to apply the concept in an unusual situation. Those trip me up.

I'm also looking at "IS - Inbound Sales Certification" as supplemental material. Is it worth going through that in detail or is the practice test approach enough?

Genuinely curious what percentage of the IS exam is dedicated to this area.